Outdoor air pollution and emergency department visits for asthma among children and adults: A case-crossover study in northern Alberta, Canada

Table 1 Number of emergency department visits for asthma, by age-group, sex, and season

Characteristic	Number of visits	%
Age (in years)
2 – 4	7,247	12.5
5 – 14	13,145	22.7
15 – 24	11,616	20.1
25 – 44	13,300	23.0
45 – 64	7,899	13.6
65 – 74	2,850	4.9
≥ 75	1,855	3.2
Sex
Male	27,926	48.2
Female	29,986	51.8
Season
Spring/Summer (April to September)	30,576	52.8
Fall/Winter (October to March)	27,336	47.2
Total visits	57,912	100.0

ISSN: 1476-069X